Well said, sir.
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-----Original Message-----
From: RPG400-L <rpg400-l-bounces@xxxxxxxxxxxxxxxxxx> On Behalf Of John Yeung
Sent: Thursday, September 19, 2019 11:51 AM
To: RPG programming on the IBM i (AS/400 and iSeries) <rpg400-l@xxxxxxxxxxxxxxxxxx>
Subject: OMG MOVE sucks!
I apologize in advance for the following rant.
I know people like to extol the virtues of "proper" ILE (modules, prototypes, etc.) and often tend to minimize the value of RPG IV when used "merely" as RPG III or RPG/400 with slightly massaged syntax.
But damn, some of those "little" niceties turn out to bring huge benefits!
Today's hero of no-"proper"-ILE-knowledge-required features is EVAL. I just spent an embarrassing amount of time tracking down weird behavior that boils down to: Someone didn't realize that two character fields were different length, and they used MOVE when they should have used... well, they SHOULD have used EVAL, but even in pure RPG III they should have used MOVEL.
I have no idea why it wasn't a shop standard to always use MOVEL when assigning character fields (pre-EVAL). I would *hope* that most programmers came to this convention on their own. I know reference manuals are supposed to be neutral and matter-of-fact, but really, in this case, there really should have been guidance *in the manual* that you NEVER use MOVE if MOVEL will do the job. (I get that not everyone reads the manual, but if it's in the manual, then at least there's a better chance that educators and mentors will be exposed to it and pass it on.)
EVAL also happens to take care of the (P) extender, which is all too easy to forget (if you know about it at all). So, I hope no one is using ANY of the MOVE* family anymore. I don't think there are any excuses left (and haven't been for many years now).
The closest thing to an excuse I would accept (and I wouldn't accept it, it's just the closest) is that some people are taught that it's a virtue to preserve the style of any existing code that you're going in to modify. I can understand why this is desirable. But it presupposes that the existing code is of a certain minimal level of quality, and that you should put aside your own *aesthetics* for the sake of cohesiveness and regularity in the code base. I would contend that we should consider MOVE* a bug, not merely a style we disagree with. It should be classified under "if this works, it's only an accident, and we've been lucky so far".
If you find yourself dealing with a program which is chock full of
MOVE* and you need to add one line but you don't have time to eradicate MOVE* from the whole program, in my book it is justified to just use EVAL on that line you're adding and leave the rest of the program as-is. Yeah, you're introducing an inconsistency in the style, but at least you're not adding a new bug.
OK, sorry, had to vent a little. Now back to our regularly scheduled programming.
John Y.
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